20 PEOCEEDINGS OF THE NATIONAL MUSEUM vol.81 



diameter. Mehlis's gland and the ootype lie on the midline and 

 slightly caudal to the ovary. Laurer's canal was not located. The 

 uterus is a much coiled structure, running caudad between the 

 testes ; after filling the body behind the testes with its coils it returns 

 anteriorly by the same course. It passes dorsal to the center of the 

 acetabulum, loops to the left, and runs parallel and ventral to the 

 cirrus sac throughout the length of that organ. The eggs measure 

 40/u, by 21/x. The vitellaria are lateral and are divided by the acetab- 

 ulum into two fields on each side. The posterior fields extend from the 

 middle of the testes to the middle of the ovary. The anterior fields 

 extend from the intestinal fork to the level of the tip of the cirrus 

 sac. They usually overlie the ceca, but do not extend median to them. 



Host. — Heterodon contortrix. 



Habitat. — Mouth. 



Locality. — Houston, Tex. 



Type sjyecwien.—U.^.'^M. Helm. Coll. No. 30881. 



Remarks. — The foregoing description is based on five specimens 

 of flukes taken from two snakes. Renifer ellipticus is recorded from 

 this same host, but the two forms are easily distinguished by the 

 location of the genital pore and the division of the vitellaria. 



Renifer texanus seems to be most closely related to R. acetahulans 

 Crow, but the cirrus sac in that form does not cross the median line, 

 nor reach the acetabulum, and there is an esophagus present. 



RENIFER KANSENSIS Crow, 1913 



Renifer Jcansensis Crow and R. ancistrodontis MacCallum are both 

 described from specimens taken from the mouth of copperhead 

 snakes {Agkistrodon iiiokasen). R. ancistrodontis is described as 

 having the genital pore on the right side, while in R. hansensis it is 

 described on the left side. Since helminthologists seem to be rather 

 careless about considering the inverting power of the microscope, this 

 character may be due to an error. Other differences between Crow's 

 and MacCallum's species are : The location of the testes, the ratio of 

 the oral sucker to the acetabulum, the position of the caudal end of 

 the cirrus sac, and the location of the genital pore. With the excep- 

 tion of the last-named difference the variation in my material is 

 practically as great as the differences noted. Crow (1913) describes 

 the genital pore as being on the left side, at the level of the posterior 

 margin of the pharynx; MacCallum (1921) as being on the right 

 side, in advance of the intestinal fork. In my material the genital 

 pore is on the right side, at the level of the pharynx. There seems 

 to be no way of settling this point definitely without the specimens ; 

 therefore, I refer my material, which was found in the mouth of 

 Agkistrodon mokasen and Sisti^rus miliariu^, to R. kansensis and 

 regard R. ancistrodontis as a species inquirenda. 



